Solar concentrator

ABSTRACT

A solar concentrator comprises an incidence surface, a first reflective curved surface corresponding to the incidence surface, a second reflective curved surface disposed in a center part of the incidence surface, and a concentrating part disposed in a center part of the first reflective curved surface and corresponding to the second reflective curved surface, wherein the incidence surface, the first reflective curved surface, the second reflective curved surface, and the concentrator include a substantially same material from each other.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2010-0043411, filed on May 10, 2010, and all the benefits accruing therefrom under U.S.C. §119, the content of which in its entirety is herein incorporated by reference.

BACKGROUND

1) Field

This disclosure generally relates to a solar concentrator.

2) Description of the Related Art

A solar cell is a photoelectric conversion device that transforms photonic energy, e.g., solar energy, into electrical energy, and has been recognized as a renewable, pollution-free next generation energy source.

The solar cell typically includes a photoelectric conversion device transforming solar energy into electrical energy, and a solar concentrator collecting solar light to improve an efficiency of the solar cell.

In general, a photoelectric conversion device, e.g., a solar cell, includes p-type and n-type semiconductors and produces electrical energy by transferring electrons and holes to the n-type and p-type semiconductors, respectively, and then collecting electrons and holes in electrodes when an electron-hole pair (“EHP”) is produced due to photonic energy, e.g., solar light energy, absorbed in a photoactive layer inside the semiconductors.

Further, a silicon solar cell may be classified into a monocrystalline type solar cell or a polycrystalline type silicon solar cell which are both based on a crystalline silicon wafer and a thin film silicon type solar cell disposed on a glass substrate. The crystalline silicon wafer type solar cell has benefits, such as reduced degeneration and a silicon thickness of several micrometers (μm) is substantially enough for generating electricity by absorbing solar light, but the costs of manufacturing a silicon wafer are high. On the other hand, the thin film silicon type solar cell may be broadly classified into an amorphous silicon solar cell, a microcrystalline silicon solar cell, and a polycrystalline silicon solar cell. The amorphous silicon solar cell has drawbacks, such as increased degeneration of light transmitting characteristics with a passage of time, although the amorphous silicon solar cell shows high photo-absorption in the visible light region and the amorphous silicon solar cell is formed with a relatively thin thickness.

The solar cell generates electrical energy in proportion to an incident light amount. A solar concentrator is beneficial for concentrating the widely-entered solar light since the solar cell typically has a substantially small size, and therefore the solar concentrator aids in the absorption of a substantially large amount of the incident light.

The solar concentrator concentrates the solar light into a solar cell by optically controlling light passage therethrough, but the light efficiency of solar concentrators has reached only about 70 percent (%) to about 80%. Thereby, an increase in the solar concentrator efficacy could greatly aid an efficiency improvement of a solar photovoltaic cell.

SUMMARY

One embodiment of a solar concentrator substantially decreases solar light loss during a concentration of the solar light, so as to improve an efficiency of a solar photovoltaic cell.

In one embodiment, the solar concentrator may substantially enhance the yield by simplifying a process of manufacturing a solar concentrator and saving costs, so it may be mass-produced.

One embodiment of the solar concentrator includes an incidence surface; a first reflective curved surface corresponding to the incidence surface; a second reflective curved surface disposed in a center part of the incidence surface; and a concentrating part disposed in a center part of the first reflective curved surface and corresponding to the second reflective curved surface, wherein the incidence surface, the first reflective curved surface, the second reflective curved surface, and the concentrator include a substantially same material.

In one embodiment, an outer side of first reflective curved surface may be subjected to a reflection process.

In one embodiment, the center part of the incidence surface may be provided with a concave portion, and an outer side of the concave portion is subjected to a reflection process to provide a second reflective curved surface.

In one embodiment, the first reflective curved surface may have a curved surface for reflecting light transmitted into the incidence surface and for reaching the second reflective curved surface.

In one embodiment, the second reflective curved surface may have a curved surface for reflecting the light incident to the second reflective curved surface to transmit the light to the concentrating part.

In one embodiment, the concentrating part may include a concentrating part incidence surface, a concentrating part emission surface, and a total reflective surface connecting the concentrating part incidence surface and the concentrating part emission surface.

In one embodiment, the concentrating part incidence surface may have a wider area than an area of the concentrating part emission surface.

In one embodiment, the total reflective surface may be substantially tilted with respect to a center axis of the concentrating part.

In one embodiment, the first reflective curved surface may be connected to the concentrating part emission surface incidence surface through an inner surface.

In one embodiment, the inner surface may be substantially parallel to the center axis of the concentrating part.

In one embodiment, the inner surface may be substantially symmetrical with the total reflective surface on the basis of a plane substantially parallel to the center axis of the concentrating part.

In one embodiment, the emission surface of the concentrating part may be positioned higher than a lowest part of the first reflective curved surface.

In one embodiment, the incidence surface may be connected to the first reflective curved surface through a side surface.

In one embodiment, the side surface may have four surfaces each of which is substantially parallel to the center axis of the solar concentrator.

In one embodiment, the concentrating part may be disposed such that a height of the concentrating part allows a light reflecting passage from the first reflective curved surface to the second reflective curved surface.

An amount of solar light emitted from the solar concentrator though the concentrating part may be more than about 80 percent (%) when the amount of solar light entering into the incidence surface is considered to be 100%.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, advantages and features of this disclosure will become more apparent by describing in further detail embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view showing one embodiment of a solar concentrator;

FIG. 2 is a cross-sectional view of the solar concentrator along line II-II in FIG. 1;

FIG. 3 is a cross-sectional view of the solar concentrator along line III-III in FIG. 1;

FIG. 4 is a perspective view showing an opposite side of the solar concentrator as that shown in FIG. 1;

FIG. 5 shows an embodiment of the passage of transmitted solar light in one embodiment of a solar concentrating part;

FIG. 6 shows a relationship between a second reflective curved surface and the solar concentrating part in the embodiment of the solar concentrator shown in FIG. 1;

FIG. 7 is a perspective view showing one embodiment of a solar concentrator array;

FIGS. 8 and 9 show solar light concentrating simulations with the embodiment of the solar concentrator shown in FIG. 1;

FIG. 10 is a cross-sectional view showing another embodiment of the solar concentrator;

FIG. 11 shows a relationship between the second reflective curved surface and the concentrating part in the embodiment of the solar concentrator shown in FIG. 10;

FIG. 12 illustrates a rotating reference plane of a structure of the embodiment of the solar concentrator shown in FIG. 1;

FIG. 13 illustrates a rotating reference plane of a structure of the embodiment of the solar concentrator shown in FIG. 10; and

FIG. 14 is a cross-sectional view showing another embodiment of the solar concentrator.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the general inventive concept will hereinafter be described in detail referring to the following accompanied drawings and may be easily performed by those who have common knowledge in the related field. However, these embodiments are only exemplary, and this disclosure is not limited thereto.

It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the general inventive concept.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element's relationship to another element as illustrated in the Figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. For example, if the device in one of the figures is turned over, elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. The exemplary term “lower,” can therefore, encompasses both an orientation of “lower” and “upper,” depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of above and below.

In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity. Like reference numerals designate like elements throughout the specification. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the general inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Hereinafter, embodiments of the present invention will be described in further detail with reference to the accompanying drawings.

Referring to FIGS. 1 to 6, an embodiment of a solar cell according to the general inventive concept is described in detail.

FIG. 1 is a perspective view showing an embodiment of the solar concentrator; FIG. 2 is a cross-sectional view of the solar concentrator along line II-II in FIG. 1; FIG. 3 is a cross-sectional view of the solar concentrator along line III-III in FIG. 1; FIG. 4 is a perspective view showing an opposite side of the embodiment of the solar concentrator shown in FIG. 1; FIG. 5 shows an embodiment of a passage of transmitted solar light in a solar concentrating part; and FIG. 6 illustrates a relationship between a second reflective curved surface and a concentrating part in the embodiment of the solar concentrator shown in FIG. 1.

One embodiment of the solar concentrator 100 includes an incidence surface 130, a first reflective curved surface 110, a second reflective curved surface 150, a concentrating part 170, a side surface 120, and an inner surface 160. The embodiment of the solar concentrator 100 includes one material having a constant refractive index, and an outer surface of the first reflective curved surface 110 and an outer surface of the second reflective curved surface 150 are treated to form a reflective metal layer so as to provide a reflective surface such as a mirror or other various types of reflective surfaces. In one exemplary embodiment, the solar concentrator 100 is integrally formed of one material having a constant refractive index, and the outer surface of the first reflective curved surface 110 and the outer surface of the second reflective curved surface 150 are treated to form a reflective metal layer so as to provide a reflective surface such as a mirror or other various types of reflective surfaces.

In one embodiment, the incidence surface 130 may be formed in a quadrangular plane, and in one embodiment, it may be a square plane as shown in FIG. 1. When solar light enters into the incidence surface 130, the incident solar light is transmitted to the first reflective curved surface 110 disposed under the incidence surface 130. The second reflective curved surface 150 is disposed in a center part of the incidence surface 130.

In one embodiment, the second reflective curved surface 150 may be a concave portion having a curved surface, and an outside of the concave portion is treated to provide a reflective metal layer. In one embodiment, the second reflective curved surface 150 is formed with a spherical or parabolic surface. In one embodiment, the second reflective curved surface 150 has a diameter R1 that equals to or less than about 1/10 of a diameter of the incidence surface 130.

In one embodiment, the first reflective curved surface 110 may be spherical or parabolic, and an outside of the first reflective curved surface is treated to provide a reflective metal layer. The first reflective curved surface 110 is disposed at a position corresponding to the incidence surface 130, and the incidence surface 130 projected upon the first reflective curved surface 110 in a center axis 111 direction is substantially similar to the first reflective curved surface 110. The first reflective curved surface 110 reflects the solar light transmitted through the incidence surface 130 and to the inside of the solar concentrator 100 to the second reflective curved surface 150, which is a significant light gathering surface for concentrating solar light which has entered through the wide incidence surface 130 to the narrow second reflective curved surface 150. That is, the first reflective curved surface 110 has a curvature to concentrate the light that perpendicularly enters into the incidence surface 130 to the second reflective curved surface 150.

Referring to FIG. 2, the first reflective curved surface 110 includes an opening 115 in the center part on its center axis 111. The opening 115 has a predetermined depth (H), and an inner surface 160 of the opening 115 includes a surface substantially parallel to the center axis 111, specifically, a cylindrical surface centered in the center axis 111. The surface of the opening 115 that is perpendicular to the center axis 111 (hereinafter referred to as the vertical surface opening) has a diameter R2 that is substantially smaller than the diameter R1 of the second reflective curved surface 150.

The concentrating part 170 is disposed in the opening 115 (also referred to as a “vertical surface opening”). The concentrating part 170 includes a concentrating part incidence surface 171, a total reflection surface 172, and a concentrating part emission surface 173. The concentrating part incidence surface 171 is an imaginary surface where the solar light reflected from the second reflective curved surface 150 enters the solar concentrator 100. In other words, since the inside of the solar concentrator 100 includes a substantially same material as the concentrating part 170, it does not cause substantial loss of the solar light which enters into the concentrating part 170. The concentrating part incidence surface 171 has a diameter R2 that is substantially the same as the diameter of the vertical surface opening 115.

The solar light entering into the concentrating part incidence surface 171 is emitted to the concentrating part emission surface 173. The concentrating part emission surface 173 has a diameter R3 that is substantially smaller than the diameter R2 of the concentrating part incidence surface 171, thereby the light having entered the solar concentrator 100 is further concentrated. Referring to FIG. 5, the solar light having entered the concentrating part incidence surface 171 is emitted to the concentrating part emission surface 173, or the solar light is totally reflected on the total reflection surface 172 on the side of the concentrating part 170, and then emitted to the concentrating part emission surface 173. The total reflection surface 172 emits the light reflected from the second reflective curved surface 150 to the concentrating part emission surface 173 without causing substantial light loss. In addition, as described above, an additional reflecting treatment is advantageously not required outside of the total reflection surface 172 disposed in the opening 115 when the solar concentrator 100 is fabricated. Therefore, the total reflection surface 172 may have an angle that satisfies the total reflection condition such that the light reflected from the second reflective curved surface 150 is totally reflected to reach the concentrating part emission surface 173.

The concentrating part 170 has a substantially same height (H) as the depth of the opening 115, and the concentrating part 170 and the opening 115 may each have a height (H) that allows the light reflected from the first reflective curved surface 110 from transmitting to the second reflective curved surface 150. The above mentioned feature will be further described in detail with reference to FIG. 6.

Referring to FIG. 6, the second reflective curved surface 150 has a diameter R1, and the vertical surface opening 115 and the concentrating part incidence surface 171 have a substantially smaller diameter than R1. A maximum depth of the opening 115 (also referred to as Hh or the highest height of the concentrating part 170) may be calculated with reference to light paths L1 and L2 as shown in FIG. 6, and the maximum depth of the opening 115 (also referred to as the height of the concentrating part 170) may be substantially smaller than or substantially the same as the calculated value. When the concentrating part 170 has the highest height (Hh), the concentrating part incidence surface 171 has the maximum diameter (R2 h). In other words, the diameter of the concentrating part incidence surface 171 is dependent upon the height of the concentrating part 170.

Still referring to FIG. 6, the light path L1 indicates a nearest light path to the center axis 111 among light paths entering through the incidence surface 130. The light entering the incidence surface nearer to the center axis 111 than the light path L1 may not enter the solar concentrator 100 due to the reflective metal layer (or reflection treatment) disposed on the outside of the second reflective curved surface 150. L1 light is reflected by the first reflective curved surface 110 to the second reflective curved surface 150 along the light path L2. If the light path L2 is blocked by the depth of the opening 115 or the height of the concentrating part 170, a concentrating efficiency of the solar concentrator 100 is deteriorated, so the depth of the opening 115 or the height of the concentrating part 170 may be formed with a height that allows the light path L2. As a result, the highest height of the concentrating part 170 is referred to as the highest height Hh in FIG. 6. In this embodiment, the concentrating part incidence surface 171 has the maximum diameter of R2 h.

In one embodiment, a diameter of the vertical surface opening 115 is also dependent upon the diameter of the concentrating part incidence surface 171. The concentrating part incidence surface 171 may have a substantially same diameter as the diameter of the vertical surface opening 115 in FIG. 1, for example.

The outside of the first reflective curved surface 110 and the outside of the incidence surface 130 are continued through the side surface 120. The side surface 120 includes four surfaces substantially parallel to the center axis 111, and the four surfaces have a substantially same shape and size from each other. A shortest distance from the first reflective curved surface 110 to the incidence surface 130 is the lowest height s substantially parallel to the direction of the center axis 111. In one embodiment, the lowest height s may be almost equal to 0.

The solar concentrator 100 may include a material of glass or plastic such as polymethyl methacrylate (PMMA) or other materials with similar characteristics. In one embodiment, the material may be obtained by molding using a mold. Thereby, it is possible to simplify a process of manufacturing the solar concentrator 100.

In one embodiment, the solar concentrator 100 may be integrally formed of a material of glass or plastic such as polymethyl methacrylate (PMMA) or other materials with similar characteristics. In one embodiment, the material may be obtained by molding using a mold. Thereby, it is possible to simplify a process of manufacturing the solar concentrator 100

The solar concentrator 100 has a substantially symmetrical structure with respect to a surface including the center axis 111 (e.g., the surface including the section line II-II or the sectioning line III-III of FIG. 1), and the first reflective curved surface 110, the second reflective curved surface 150, the opening 115, and the concentrating part 170 included in the solar concentrator are also substantially symmetrical with respect to the surface including the center axis 111.

A photoelectric conversion device, e.g., solar cell (not shown), converting solar light into electrical energy is closely disposed at the outside of the concentrating part emission surface 173. Since the solar concentrator 100 has a structure such that solar light perpendicular to the incidence surface is concentrated, the solar concentrator 100 may further include a tracker (not shown) shifting the direction of the solar concentrator 100 according to movement of the sun.

FIG. 7 is a perspective view showing an embodiment of a solar concentrator array.

One solar concentrator 100 may be provided in each solar cell, and in one embodiment, a pair of a solar concentrator 100 and a solar cell may be arranged in an array. In the present embodiment, the embodiment of the solar concentrator 100 may be integrally formed using one mold with an array structure. An embodiment of the integrally formed solar concentrator array is shown in FIG. 7.

In the present embodiment, side surfaces 120 of solar concentrators 100 are connected to each other. The lowest height s of each side surface 120 may be an area where the adjacent solar concentrators 100 are integrally connected to each other.

FIGS. 8 and 9 show a simulation of concentrating solar light by the embodiment of the solar concentrator shown in FIG. 1.

FIG. 8 shows a structure in which a solar cell 200 is closely disposed under the solar concentrator. In one embodiment, the solar cell 200 is closely disposed to the emission surface 173 of the concentrating part of the solar concentrator.

Although FIGS. 8 and 9 show the solar light reflected from the first reflective curved surface and the solar light reflected from inside the solar concentrator to the second reflective curved surface when the solar light enters into the incidence surface, FIGS. 8 and 9 are not cross-sectional views of a solar concentrator but are perspective views with different angles, so the reflected parts may appear different from each other. That is, all the solar light is reflected by the first reflective curved surface, but it appears as if it is reflected in a variety of places without considering the first reflective curved surface in a perspective view.

FIGS. 8 and 9 show simulations based on an embodiment that the solar concentrator includes a material of BK7 glass, and the first reflective curved surface and the second reflective curved surface are treated with silver or other materials with similar characteristics, for example, to be reflective.

In one embodiment, the solar concentrator is formed of a material of BK7 glass, and the first reflective curved surface and the second reflective curved surface are treated with silver or other materials with similar characteristics, for example, to be reflective.

The following Table 1 illustrates the results of the simulation.

TABLE 1 Light efficiency (%) Wavelength of Light 500 nm 650 nm 800 nm 1100 nm Incidence 100 100 100 100 surface First reflective 95.11 95.22 95.30 95.33 curved surface Second 89.38 91.59 92.77 92.74 reflective curved surface Incidence 84.20 88.13 90.30 90.24 surface of concentrating part Emission 84.13 88.07 90.26 90.18 surface of concentrating part

Table 1 indicates the light amount entering each surface in each wavelength band.

In other words, considering the amount of light having a wavelength of 500 nm in the incidence surface 130 as 100 percent (%), it shows that about 95.11% of the light arrives at the first reflective curved surface 110; about 89.38% of the light arrives at the second reflective curved surface 150; about 84.20% of the light arrives at the concentrating part incidence surface 171; and about 84.13% of the light arrives at the concentrating part emission surface 173. It is confirmed that the light efficiency is lowest with about 84.13% at 500 nm and highest with about 90.26% at 800 nm.

One embodiment of the solar concentrator 100 only has an interface between an outside (e.g., air) and the incidence surface 130, and between the concentrating part emission surface 173 and the outside (e.g., air) which are different materials from each other, so it may substantially decrease light loss because of the minimal number of interfaces. Therefore, the embodiment of the solar concentrator 100 shown in FIG. 1 has light efficiency of more than about 84%, so it may convert substantially more solar light incident to electrical energy per unit area. In addition, it may generate relatively substantially more electrical energy by using a solar concentrator array.

Although the embodiment of the solar concentrator shown in FIG. 1 has light efficiency of more than about 84%, the solar concentrator is considered to have at least about 80% light efficiency considering manufacturing tolerance among products and errors depending upon the wavelength or other similar characteristics.

Hereinafter, another embodiment according to the general inventive concept will be described referring to FIGS. 10 and 11.

FIG. 10 is a cross-sectional view of another embodiment of a solar concentrator, and FIG. 11 shows a relationship between the second reflective curved surface and the concentrating part in the embodiment of the solar concentrator shown in FIG. 10.

An embodiment of the solar concentrator 100 includes an incidence surface 130, a first reflective curved surface 110, a second reflective curved surface 150, a concentrating part 170, a side surface 120, and an inner surface 160. Differing from the embodiment of the solar concentrator shown in FIG. 1, in the embodiment of the solar concentrator shown in FIG. 10, the inner surface 160 is substantially tilted with respect to the center axis 111, and the inner surface 160 may be substantially symmetrical to the total reflection surface 172 on the basis of a surface substantially parallel to the center axis 111.

The solar concentrator 100 includes one material having a constant refractive index, and the outside surfaces of the first reflective curved surface 110 and the second reflective curved surface 150 are treated with a metal layer to provide a reflective surface such as a mirror or other materials with similar characteristics.

In one embodiment, the solar concentrator 100 is integrally formed of one material having a constant refractive index, and the outside surfaces of the first reflective curved surface 110 and the second reflective curved surface 150 are treated with a metal layer to provide a reflective surface such as a mirror or other materials with similar characteristics.

In one embodiment, the incidence surface 130 has a quadrangular plane or square plane shape. The solar light enters into the incidence surface 130 and the solar light is transmitted to the first reflective curved surface 110 under the incidence surface 130. A second reflective curved surface 150 is disposed in a center part of the incidence surface 130.

The second reflective curved surface 150 includes a concave portion, and the outside of the concave portion is treated to provide a reflective metal layer. The second reflective curved surface 150 has a spherical or parabolic surface. The second reflective curved surface 150 has a diameter R1 that equals to or smaller than about 1/10 of the diameter of incidence surface 130.

The first reflective curved surface 110 is spherical or parabolic, and the outside of the first reflective curved surface is treated to provide a reflective metal layer. The first reflective curved surface 110 is disposed at a position corresponding to the incidence surface 130, and the first reflective curved surface 110 appears substantially the same as the incidence surface 130 when projecting the first reflective curved surface 110 in a direction of the center axis 111. The first reflective curved surface 110 reflects the solar light transmitted from the incidence surface 130 and to the inside of the solar concentrator 100 to the second reflective curved surface 150, which is a significant light gathering surface for concentrating solar light having entered through the wide incident surface 130 into the narrow second reflective curved surface 150. That is, the first reflective curved surface 110 has a curvature to concentrate the light that perpendicularly enters into the incidence surface 130 to the second reflective curved surface 150.

The first reflective curved surface 110 includes an opening 115 in the center part on the basis of the center axis 111. The opening 115 has a predetermined depth (H), and the inner surface 160 of the opening 115 includes a substantially tilted surface with respect to the center axis 111. The inner surface 160 may be formed with an angle which is substantially symmetrical with the total reflection surface 172 of the concentrating part 170 on the basis of a line substantially parallel to the center axis 111. The surface 116 of the opening 115 that is perpendicular to the center axis 111 (hereinafter referred to as the vertical surface opening) may have a diameter that equals to or smaller than R1, and that is substantially larger than R2.

The concentrating part 170 is disposed in the opening 115. The concentrating part 170 includes a concentrating part incidence surface 171, a total reflection surface 172, and a concentrating part emission surface 173. The concentrating part incidence surface 171 is an imaginary surface where the solar light reflected from the second reflective curved surface 150 enters the solar concentrator 100. That is, since the inside of solar concentrator 100 includes substantially a same material as the concentrating part 170, the solar light is not lost when entering the concentrating part 170. The concentrating part incidence surface 171 has a diameter R2 that is substantially smaller than the vertical surface opening 115. In one embodiment, the inside of solar concentrator 100 is formed of a substantially same material as the concentrating part 170, the solar light is not lost when entering the concentrating part 170.

The solar light entering the concentrating part incidence surface 171 is emitted to the concentrating part emission surface 173. The concentrating part emission surface 173 has a diameter R3 that is substantially smaller than diameter R2 of the concentrating part incidence surface 171, so the light having entered the solar concentrator 100 is further concentrated. The solar light having entered the concentrating part incidence surface 171 is directly emitted to the concentrating part emission surface 173 or is totally reflected on the total reflection surface 172 on the side of the concentrating part 170 to be emitted to the concentrating part emission surface 173. The total reflection surface 172 emits the light reflected from the second reflective curved surface 150 to the concentrating part emission surface 173 without substantial light loss. In addition, it provides merits that an additional reflection process is not required with regard to the opening 115 when a solar concentrator 100 is fabricated. Therefore, the total reflection surface 172 has an angle that satisfies the total reflection condition that the light reflected from the second reflective curved surface 150 is totally reflected to reach the concentrating part emission surface 173.

The concentrating part 170 has substantially the same height (H) as the depth of the opening 115, and the concentrating part 170 and the opening 115 may be formed with a height (H) that allows the light reflected from the first reflective curved surface 110 from transmitting to the second reflective curved surface 150. The above mentioned features will be further described in detail with reference to FIG. 11.

The second reflective curved surface 150 has a diameter R1, and the opening 115 and the concentrating part incidence surface 171 have a substantially smaller diameter than R1. The maximum depth of the opening 115 (referred to as Hh or the highest height of the concentrating part 170) may be calculated with reference to light paths L1 and L2 as shown in FIG. 11, and the depth of the opening 115 (or the height of the concentrating part 170) may be substantially smaller or substantially the same as the calculated value. When the concentrating part 170 has the highest height (Hh), the concentrating part incidence surface 171 has the maximum diameter (R2 h). The diameter of the concentrating part incidence surface 171 is dependent upon the height of the concentrating part 170.

In FIG. 11, L1 indicates to the nearest light path to the center axis 111 among light paths through the incidence surface 130. The light entering the incidence surface nearer to the center axis 111 than L1 does not enter the solar concentrator 100 due to the metal layer (or reflection treatment) disposed on the outside of the second reflective curved surface 150. L1 light is reflected by the first reflective curved surface 110 to the second reflective curved surface 150 along the L2 light path. If the passage of L2 light is blocked by the opening 115 and the concentrating part 170, the concentrating efficiency of the solar concentrator 100 is deteriorated, so the opening 115 and the concentrating part 170 may be formed with a height that allows the passage of the light L2. As a result, the highest height of the concentrating part 170 is referred to as Hh in FIG. 11. In this embodiment, the concentrating part incidence surface 171 has the maximum diameter R2 h.

In one embodiment, the inner surface 160 of the opening 115 may be also substantially tilted with respect to the center axis 111 within the range which allows the passage of L2. Thereby, the vertical surface opening 115 may be changed according to the above mentioned range. In one embodiment, the vertical surface opening 115 may have a substantially smaller diameter than the diameter R2 of the second reflective curved surface.

The outside of the first reflective curved surface 110 and the outside of the incidence surface 130 are continued through the side surface 120. The side surface 120 includes four surfaces substantially parallel to the center axis 111, and the four surfaces have substantially the same shape and size. The shortest distance from the first reflective curved surface 110 to the incidence surface 130 is s in the direction of the center axis 111. In one embodiment, a length of s may be almost equal to 0.

In one embodiment, the solar concentrator 100 may include a material of glass or plastic such as PMMA or other materials with similar characters. In one embodiment, the material may be obtained by a molding process using a mold. Thereby, it is possible to simplify the process of manufacturing the solar concentrator 100.

In one embodiment, the solar concentrator 100 may be integrally formed of a material of glass or plastic such as PMMA or other materials with similar characters

The solar concentrator 100 has a substantially symmetrical structure with respect to the center axis 111, and the first reflective curved surface 110, the second reflective curved surface 150, the opening 115, and the concentrating part 170 included in the solar concentrator are also substantially symmetrical with respect to the center axis 111.

A photoelectric conversion device (e.g., solar cell, not shown) converting solar light into electrical energy is closely disposed at the outside of the concentrating part emission surface 173. The solar concentrator 100 has a structure such that solar light perpendicular to the incidence surface is concentrated, so the solar concentrator 100 may further include a tracker (not shown) shifting the direction of the solar concentrator 100 according to movement of the sun.

One solar concentrator 100 is provided in each solar cell, and in one embodiment, a pair of a solar concentrator 100 and a solar cell may be generally arranged in an array. In the present embodiment, the solar concentrator 100 may be integrally formed using one mold with an array-arranged structure.

In the above mentioned embodiments, a plurality of side surfaces 120 of solar concentrators 100 is connected to each other. The lowest height s of each side surface 120 as shown in FIG. 10 is an area where the adjacent solar concentrators 100 are integrally connected to each other.

In the embodiment of the solar concentrator 100 of FIGS. 10 and 11, the inner surface 160 is substantially tilted with respect to the center axis 111. Thereby, the solar concentrator 100 may be produced substantially easier than the structure shown in FIG. 1 with regard to removing the mold of the opening 115 around the concentrating part 170.

The embodiment of the solar concentrator 100 of FIGS. 1 and 10 may be further described as follows.

First, the embodiment of the solar concentrator 100 of FIG. 1 is described with reference to FIG. 12.

FIG. 12 shows a rotating reference plane of a structure that may be rotated 360° with respect to its center axis 111 or that corresponds to the embodiment of the solar concentrator 100 shown in FIG. 1.

The rotating reference plane of FIG. 12 is illustrated with looped curves including an upper line 130-1, a side line 120-1, a lower curved line 110-1, an upper curved line 150-1, an inner line 160-1, a diagonal line 172-1, a lower line 173-1, and a center axis 111. The inner line 160-1 is substantially parallel to the center axis 111.

If the rotating reference plane is rotated 360° with respect to its center axis 111, it does not perfectly correspond to the embodiment of the solar concentrator of FIG. 1. That is because the incidence surface 130 of FIG. 1 has a quadrangular structure, but the 360°-rotated structure has a circular structure. If the 360°-rotated structure is cut into a square structure, it may correspond to the embodiment of the solar concentrator shown in FIG. 1. In one embodiment, as shown in FIG. 12, the 360°-rotated structure may be used for a solar concentrator, but the structure shown in FIG. 1 is more easily connected to arrange an array structure than the 360°-rotated structure based on an embodiment of the rotating reference plane shown in FIG. 12.

In FIG. 12, the upper line 130-1 corresponds to the incidence surface 130; the side line 120-1 corresponds to the side surface 120; the lower curved line 110-1 corresponds to the first reflective curved surface 110; the upper curved line 150-1 corresponds to the second reflective curved surface 150; the inner line 160-1 corresponding to the inner surface 160; and the diagonal line 172-1 and the lower line 173-1 correspond to the concentrating part 170.

The solar concentrator 100 shown in FIG. 10 will now be further described with reference to FIG. 13.

FIG. 13 shows a rotating reference plane of a structure that may be rotated 360° with respect to its center axis 111 or that corresponds to the embodiment of the solar concentrator 100 shown in FIG. 10.

The rotating reference surface plane of FIG. 13 is illustrated by a looped curved line composed of an upper line 130-1, a side line 120-1, a lower curved line 110-1, an upper curved line 150-1, an inner line 160-2, a diagonal line 172-1, a lower line 173-1, and a center axis 111. The inner line 160-2 is substantially tilted with regard to the center axis 111, differing from FIG. 12.

If the rotating reference plane is rotated 360° with respect to its center axis 111, it does not perfectly correspond to the embodiment of the solar concentrator 100 of FIG. 10. That is because the incidence surface 130 of FIG. 10 has a quadrangular structure, but the 360°-rotated structure has a circular structure. If the 360°-rotated structure is cut into a square structure, it may correspond to the embodiment of the solar concentrator shown in FIG. 10. In one embodiment, as shown in FIG. 13, the 360°-rotated structure may be used for a solar concentrator as it is, but the structure shown in FIG. 10 is more easily connected to arrange an array structure than the 360°-rotated structure based on an embodiment of the rotating reference plane shown in FIG. 13.

In FIG. 13, the upper line 130-1 corresponds to the incidence surface 130; the side line 120-1 corresponds to the side surface 120; the lower curved line 110-1 corresponds to the first reflective curved surface 110; the upper curved line 150-1 corresponds to the second reflective curved surface 150; the inner line 160-2 corresponds to the inner surface 160; and the diagonal line 172-1 and the lower line 173-1 correspond to the concentrating part 170. Differing from the rotating body shown in FIG. 12, the inner line 160-2 is not parallel to the center axis 111.

FIG. 14 is a cross-sectional view showing another embodiment of a solar concentrator, and is based on the structure of FIG. 10.

FIG. 14 shows that the emission surface 173 of the concentrating part 170 is disposed higher than the lowest part of the first reflective curved surface 110, differing from the embodiment of FIG. 10. In FIG. 14, a reference character g indicates a height difference between the lowest part of the first reflective curved surface 110 and the concentrating part emission surface 173.

As shown in FIG. 14, when the concentrating part emission surface 173 has a predetermined height difference (g) from the lowest part of the first reflective curved surface 110, a solar cell 200 may be disposed under the corresponding opening 115. In one embodiment, a solar cell 200 may be inserted into the corresponding opening 115.

FIG. 14 shows an embodiment of the inside surface 160 which is substantially tilted with respect to the center axis 111, but an embodiment of the inside surface 160 may be substantially parallel to the center axis 111 as shown in FIG. 2.

While this disclosure has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the general inventive concept is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

1. A solar concentrator comprising: an incidence surface; a first reflective curved surface corresponding to the incidence surface; a second reflective curved surface disposed in a center part of the incidence surface; and a concentrating part disposed in a center part of the first reflective curved surface and corresponding to the second reflective curved surface, wherein the incidence surface, the first reflective curved surface, the second reflective curved surface, and the concentrator include a substantially same material from each other.
 2. The solar concentrator of claim 1, wherein an outer side of the first reflective curved surface is a reflective surface.
 3. The solar concentrator of claim 1, wherein the center part of the incidence surface is a concave portion, and an outer side of the concave portion is a reflective surface.
 4. The solar concentrator of claim 1, wherein the first reflective curved surface has a curved surface which reflects light transmitted into the incidence surface to the second reflective curved surface.
 5. The solar concentrator of claim 4, wherein the second reflective curved surface has a curved surface which reflects the transmitted light to the concentrating part.
 6. The solar concentrator of claim 1, wherein the concentrating part comprises a concentrating part incidence surface, a concentrating part emission surface, and a total reflective surface connecting the concentrating part incidence surface to the concentrating part emission surface.
 7. The solar concentrator of claim 6, wherein the concentrating part incidence surface has a greater area than an area of the concentrating part emission surface.
 8. The solar concentrator of claim 7, wherein the total reflective surface is substantially tilted with respect to a center axis of the concentrating part.
 9. The solar concentrator of claim 8, wherein the first reflective curved surface is connected to the concentrating part incidence surface through an inner surface.
 10. The solar concentrator of claim 9, wherein the inner surface is substantially parallel to the center axis of the concentrating part.
 11. The solar concentrator of claim 9, wherein the inner surface is substantially symmetrical with the total reflective surface about a plane substantially parallel to the center axis of the concentrating part.
 12. The solar concentrator of claim 6, wherein the concentrating part emission surface is positioned higher than a lowest part of the first reflective curved surface when the incidence surface is positioned higher than the first reflective curved surface.
 13. The solar concentrator of claim 1, wherein the incidence surface is connected to the first reflective curved surface through a side surface.
 14. The solar concentrator of claim 13, wherein the side surface has four surfaces, and each of the four surfaces is substantially parallel to the center axis of the solar concentrator.
 15. The solar concentrator of claim 1, wherein the concentrating part is disposed such that a height of the concentrating part allows a passage of light reflected from the first reflective curved surface to the second reflective curved surface.
 16. The solar concentrator of claim 1, wherein an amount of solar light emitted from the solar concentrator though the concentrating part is more than about 80% of all light incident to the incidence surface. 